1. Field of the Invention
The present invention relates to a rotary ring seal with gasdynamic lubrication for high-speed turbomachines, particularly gas turbine engines, in which one of two complementary mating rings is radially traversed by apertures which extend in parallel with the ring sealing face and which are supplied with a cooling liquid.
High-speed rotary ring seals, rotating at sliding speeds of about 130 m/sec and higher, for obvious reasons the two sliding surfaces should not be allowed to remain in contact with each other over periods substantially exceeding the starting up and shutdown times, because of the danger of possible wear, heat generation and with the consequent destruction of the sealing and sliding surface.
2. Discussion of the Prior Art
Heretofore, for separating the surfaces, the following methods have been employed:
(a) Introduction of oil or other suitable hydraulic materials for separation (lubrication) of the surfaces, with, if required, subsequent evaporation, or
(b) Generation of gas or air cushions in an aerostatic or gas-dynamic manner.
The first of the above-mentioned methods, particularly where the media which are to be sealed off are gaseous, threaten to contaminate the media with the lubricating (separating) material and, where environmental or media temperatures are high, to cause carbonization of the lubricant. This method is, therefore, preferably suitable for the sealing of media which are also hydraulic (medium is equivalent to separating and lubricating medium).
The second method is adapted for the sealing off of gaseous materials, particularly wherein a gas cushion is generated gas-dynamaically.
A procedure which comes under the second-mentioned method contemplates the formation of, for example, riser surfaces, or socalled "lift pads", for the generation of the gas-dynamic lubricating wedge.
This method requires a considerable complexity in manufacture. Moreover, the thusly obtained lift pads are subjected to a relatively high degree of wear, which necessitates complicated remachining and, at times, extensive repairs.